linux-kernel - [PATCH 5.4 129/270] iomap: Make sure iomap_end is called after iomap

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Message-Id: <20200817143802.211923175@linuxfoundation.org>
Date:   Mon, 17 Aug 2020 17:15:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andreas Gruenbacher <agruenba@...hat.com>,
        Christoph Hellwig <hch@....de>,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 129/270] iomap: Make sure iomap_end is called after iomap_begin

From: Andreas Gruenbacher <agruenba@...hat.com>

[ Upstream commit 856473cd5d17dbbf3055710857c67a4af6d9fcc0 ]

Make sure iomap_end is always called when iomap_begin succeeds.

Without this fix, iomap_end won't be called when a filesystem's
iomap_begin operation returns an invalid mapping, bypassing any
unlocking done in iomap_end.  With this fix, the unlocking will still
happen.

This bug was found by Bob Peterson during code review.  It's unlikely
that such iomap_begin bugs will survive to affect users, so backporting
this fix seems unnecessary.

Fixes: ae259a9c8593 ("fs: introduce iomap infrastructure")
Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/iomap/apply.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c
index 54c02aecf3cd8..c2281a6a7f320 100644
--- a/fs/iomap/apply.c
+++ b/fs/iomap/apply.c
@@ -41,10 +41,14 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
 	ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
 	if (ret)
 		return ret;
-	if (WARN_ON(iomap.offset > pos))
-		return -EIO;
-	if (WARN_ON(iomap.length == 0))
-		return -EIO;
+	if (WARN_ON(iomap.offset > pos)) {
+		written = -EIO;
+		goto out;
+	}
+	if (WARN_ON(iomap.length == 0)) {
+		written = -EIO;
+		goto out;
+	}
 
 	/*
 	 * Cut down the length to the one actually provided by the filesystem,
@@ -60,6 +64,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
 	 */
 	written = actor(inode, pos, length, data, &iomap);
 
+out:
 	/*
 	 * Now the data has been copied, commit the range we've copied.  This
 	 * should not fail unless the filesystem has had a fatal error.
-- 
2.25.1